Advances of hyphenated technique in impurity profiling of active pharmaceutical ingredients and pharmaceutical products

Impurities found in active pharmaceutical ingredients (APIs) and pharmaceutical products are of ever‐increasing interest. According to several regulatory agencies, purity and impurity profiles are essential. An impurity is defined as any additional inorganic or organic material, residual solvents other than the medicinal components, or undesired compounds that remain with APIs. Impurities and degradation products in bulk drug materials and pharmaceutical formulations are identified, their structures are clarified, and their quantitative determination is part of impurity profiling. Unrecognized, poisonous impurities are dangerous to health and should be identified by selective procedures to increase the safety of drug therapy, and impurity profiling has become more significant in pharmaceutical analysis. This review briefly introduces process and product‐related impurities and emphasizes the creation of cutting‐edge analytical techniques for identifying them. It discusses the use of analytical methods, particularly high‐performance thin‐layer chromatography, liquid chromatography with mass spectrometry (MS), ultrahigh‐performance liquid chromatography, gas chromatography–MS, and nuclear magnetic resonance spectroscopy for the identification of contaminants and degradation products. It has discussed the importance of the quality, efficacy, and safety of drug substances and products, including the origin, types, and quality control of impurities, the need for the development of impurity profiling methods, impurity identification, and regulatory aspects.